<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>全屏高度的固定导航条</title>
    <style>
        body {
            margin: 0;
        }

        ul {
            list-style-type: none;
            margin: 0;
            padding: 0;
         /*   width: 25%;*/
            width:50px;
            background-color: #f1f1f1;
            position: fixed;
            height: 100%;
            overflow: auto;
        }

        li a {
            display: block;
            color: #000;
            padding: 8px 16px;
            text-decoration: none;
        }

        li a.active {
            background-color: #4CAF50;
            color: white;
        }

        li a:hover:not(.active) {
            background-color: #555;
            color: white;
        }
    </style>
</head>
<body>
<ul>
    <li><a class="active" href="#home">主页</a></li>
    <li><a href="#news">新闻</a></li>
    <li><a href="#contact">联系</a></li>
    <li><a href="#about">关于</a></li>
</ul>

<div style="margin-left:25%;padding:1px 16px;height:1000px;">
    <h2>Fixed Full-height Side Nav</h2>
    <h3>Try to scroll this area, and see how the sidenav sticks to the page</h3>
    <p>Notice that this div element has a left margin of 25%. This is because the side navigation is set to 25% width. If you remove the margin, the sidenav will overlay/sit on top of this div.</p>
    <p>Also notice that we have set overflow:auto to sidenav. This will add a scrollbar when the sidenav is too long (for example if it has over 50 links inside of it).</p>
    <p>Some text..</p>
    <p>Some text..</p>
    <p>Some text..</p>
    <p>Some text..</p>
    <p>Some text..</p>
    <p>Some text..</p>
    <p>Some text..</p>
</div>
</body>
</html>